EP1434042A1 - ( Sitz ) Last-Platte mit Doppelbrücke zur Temperaturkompensation - Google Patents

( Sitz ) Last-Platte mit Doppelbrücke zur Temperaturkompensation Download PDF

Info

Publication number
EP1434042A1
EP1434042A1 EP03028475A EP03028475A EP1434042A1 EP 1434042 A1 EP1434042 A1 EP 1434042A1 EP 03028475 A EP03028475 A EP 03028475A EP 03028475 A EP03028475 A EP 03028475A EP 1434042 A1 EP1434042 A1 EP 1434042A1
Authority
EP
European Patent Office
Prior art keywords
flexible substrate
sensor
strain gauges
seat
load sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03028475A
Other languages
English (en)
French (fr)
Inventor
Eiji Yanagi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Takata Corp
Original Assignee
Takata Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Takata Corp filed Critical Takata Corp
Publication of EP1434042A1 publication Critical patent/EP1434042A1/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
    • B60R21/01512—Passenger detection systems
    • B60R21/01516—Passenger detection systems using force or pressure sensing means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/002—Seats provided with an occupancy detection means mounted therein or thereon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
    • B60R21/01512—Passenger detection systems
    • B60R21/01516—Passenger detection systems using force or pressure sensing means
    • B60R21/0152—Passenger detection systems using force or pressure sensing means using strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
    • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
    • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
    • G01G19/4142—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only for controlling activation of safety devices, e.g. airbag systems

Definitions

  • the present invention relates to a load sensor for measuring a load and converting the load into an electrical signal and a seat weight measuring apparatus employing the same.
  • Automobiles are equipped with seat belt devices and airbag devices as facilities for ensuring the safety of occupants.
  • the weight body weight
  • EA energy absorbing
  • An example of such means is a proposal which involves arranging load sensors (load cell) at four comers of seat rails, obtaining vertical loads acting on the load cells, and summing them to determine the seat weight including the weight of the occupant (Japanese Patent Unexamined Publication No. H11-1153, Japanese Patent Unexamined Publication No. H11-304579, Japanese Patent Unexamined Publication No. 2000-180255).
  • Load sensor as mentioned above is preferably a small-sized one capable of measuring about 50 kg at the maximum.
  • load sensor include a sensor comprising a sensor plate which is deflected depending on the received load and a strain gauge attached to (formed on) the sensor plate, and a sensor comprising a elastic member which is deflected depending on the received load and an electrical capacitance sensor detecting the displacement of the elastic member.
  • a thick-film strain gauge may be used as the strain gauge.
  • Fig. 9 is a side view schematically showing the entire structure of a seat weight measuring apparatus as the prior art.
  • the words "front and rear”, “left and right” without any definition mean the front and rear, the left and right for an occupant 1.
  • a seat 3, an occupant 1 on the seat, and seat weight measuring apparatuses 5 beneath the seat are shown.
  • the seat 3 comprises a seat cushion 3a on which the occupant 1 sits, and a seat back 3b as a backrest.
  • Seat adjustors 10 are disposed at four locations, front and rear on both sides of the bottom of the seat cushion 3a to project from the seat cushion 3a. It should be noted that only two of the adjustors 10 are shown which are located front and rear on the left side. The adjustors 10 on the right side are behind the adjustors 10 on the left side. The same is true for the following components of this apparatus in relation on the drawing.
  • the seat adjustor 10 is an extending portion of a frame inside the seat 3 and is slidable in the front-and-rear direction on a seat rail 11 by adjustment operation of the occupant 1.
  • the seat rail 11 has a groove (not shown) and is a member extending in the longitudinal direction (front-and-rear direction) of a vehicle.
  • the lower end portion of the seat adjustor 10 can slide within and along the groove.
  • Two seat rails 11 are provided on the left and right sides beneath the seat cushion 3a, respectively.
  • the seat rails 11 are securely fixed to a seat bracket of a vehicle chassis by bolts.
  • One of the seat rails 11 is provided, at one location near the rear end thereof, with an anchor fixing portion 12 for fixing a buckle 4 of a seat belt device 2. Tension of the seat belt 2 is exerted on the anchor fixing portion 12.
  • the front and rear seat weight measuring apparatuses 5 are also provided below the right-side seat rail which is not shown. Consequently, the seat weight measuring apparatuses 5 are disposed at four locations, front and rear on both sides below the seat 3.
  • Each seat weight measuring apparatus 5 comprises a seat supporting mechanism 17 and a displacement restriction mechanism 25 and disposed between the seat rail 11 and a seat fixing portion 19.
  • the seat supporting mechanism 17 comprises a load sensor 13 and a deflection member 15 which are connected in series.
  • the load sensor 13 detects the load applied to the seat supporting mechanism 17.
  • the deflection member 15 is a member for enhancing the displacement (movement) of the seat rail 11 when the weight of the occupant is applied to the seat 3.
  • the displacement restriction mechanism 25 comprises a restriction bar 21 connected to the bottom of the seat rail 11, and a restriction block 23 formed on the seat fixing portion 19.
  • the restriction bar 21 has an end portion 21a of which diameter is enlarged just like a flange.
  • the restriction block 23 has a recess 23a inside thereof. On the top end of the recess 23a, a flange 23b extending inwardly is formed.
  • the restriction bar end portion 21a is fitted in the recess 23a of the restriction block with some spaces above and below, in front and rear, and on left and right thereof.
  • the restriction bar end portion 21 a of the displacement restriction mechanism 25 collides with the inner wall of the recess 23a of the restriction block.
  • the restriction bar 21 is pulled up to move upward.
  • the movement of the restriction bar 21 is prevented by the lower surface of the flange 23b of the restriction block.
  • the displacement restriction mechanism 25 for restricting the relative displacement between the seat and the seat fixing portion into a certain range.
  • a force over a predetermined range for example, a force exceeding the measurable range
  • the displacement restriction mechanism (load limiting mechanism) 25 not the load sensor 13. Therefore, the required mechanical strength of the load sensor 13 can be significantly reduced, thereby achieving the miniaturization and reduction in cost of the load sensor 13.
  • the space between the restriction bar end portion 21a of the displacement restriction mechanism 25 and the recess 23a of the restriction block should also be in the order of 0.1 mm, because the restriction bar end portion 21a is required to abut against the internal surface of the recess 23a of the restriction block as soon as the load exceeds the measurable range, so that the excess load is withstood by the displacement restriction mechanism 25.
  • the displacement restriction mechanism 25 is required to have an operational precision in the order of 0.1 mm corresponding to the 0.1 mm stroke of the load sensor 13, which in turn requiring the parts dimensional precision and assembly precision in the order of 0.01 mm. This can not be fulfilled at all with current dimensional precision of the peripheral parts of the vehicle seat, which mainly consist of pressed products.
  • the small deflection stroke of the load sensor 13 calls for a high dimensional precision in the displacement restriction mechanism (load limiting mechanism) 25 and the peripheral members thereof.
  • the deflection stroke of the seat supporting mechanism 17 in the measurable range or load bearing range of the load sensor 13 is amplified by the action of the deflection member 15 of the seat supporting mechanism 17.
  • the dimensional precision and assembly precision requirements for members constituting the seat supporting mechanism 17 and the displacement restriction mechanism 25 can be alleviated.
  • Figs. 10(A), 10(B) show the structure of a seat weight measuring apparatus of prior art, in which Fig. 10(A) is a general sectional side view and Fig. 10(B) is a plan view of a sensor plate. Shown in the uppermost portion of Fig. 10(A) is a seat rail 11. Under the seat rail 11, a sensor frame upper plate 31 and a sensor frame 33 are fixed by means of bolts 32.
  • the sensor frame upper plate 31 is a durable plate having a hole 31a at the center.
  • the sensor frame 33 has a saucer-like configuration with a recessed central portion.
  • a flange 33a Formed around the upper external periphery of the frame 33 is a flange 33a which is fixed to the sensor frame upper plate 31 by means of the bolts 32, as described above.
  • the bottom plate 33b of the sensor frame 33 is provided with a hole 33c formed at the center thereof.
  • a sensor plate 37 is fixed by means of bolts 35 to the lower surface of the sensor frame upper plate 31.
  • the sensor plate 37 is made of a stainless steel and is a rectangular plate with a thickness of 3 mm, a width of 20 mm, and a length of 80 mm.
  • the sensor plate 37 is provided with a central through hole 37c formed in the central portion and with bolt holes 37a formed in the both side portions.
  • Attached to the upper surface of the sensor plate 37 are resistor-type strain gauges 37b, a pair of them being attached on each front and rear portions of the plate (left and right portions in Fig 10(B)). These resistor-type strain gauges 37b are for measuring the load acting on the sensor plate 37, by detecting the distortion of the plate 37.
  • a central shaft 39 Fitted into the hole 37c located at the center of the sensor plate 37 is a central shaft 39, and the sensor plate 37 and the central shaft 39 are fixed to each other by means of a nut 39a.
  • bolts 35 are inserted upwardly, thereby fixing the sensor plate 37 to the sensor frame upper plate 31.
  • the central shaft 39 is a cylindrical shaft having several steps and flanges.
  • the central shaft 39 comprises, from its upper side, an upper nut 39a, a flange 39b, a sensor frame penetrating portion 39c, a small diameter portion 39d, a lower nut 39e, and the like.
  • the upper nut 39a fixes the sensor plate 37 as described above.
  • the nut 39a enters into the central hole 31a of the sensor frame upper plate 31. In the nominal state, the gaps between the nut 39a and the hole 31a are, for example, 0.25 mm in the vertical direction and 0.5 mm in the radial direction.
  • the nut 39a comes in contact with the internal surface of the hole 31a. At this point, the further deformation of the sensor plate 37 is stopped. That is, the nut 39a on the central shaft and the central hole 31a of the sensor frame upper plate compose the displacement restriction mechanism.
  • the outer diameter of the flange 39b of the central shaft 39 is greater than the diameter of the central hole 33c of the sensor frame 33, the lower surface of the flange 39b facing the upper surface of the sensor frame bottom plate 33b with a gap of 0.25 mm in the nominal state.
  • the small diameter portion 39d of the central shaft 39 extends downward from the sensor frame penetrating portion 39c with decreasing its diameter stepwise.
  • the nut 39e is screwed to the end of the small diameter portion 39d.
  • Fitted onto the outer periphery of the small diameter portion 39d are, from its upper side, a washer 41, a rubber washer 43, a sensor base 45, another rubber washer 43, and another washer 41.
  • the washers 41 are made of metal.
  • the rubber washers 43 expand and contract by about 0.5 mm in the sum of two sheets, upper and lower, for a load variation of about 50 kgf in the vertical direction.
  • the rubber washers 43 serve to absorb dimensional difference and distortion between the seat rail 11 and the seat fixing portion (a seat bracket 47).
  • the sensor base 45 is a metal plate and comprises a lowermost member of the seat weight measuring apparatus.
  • the upper and lower washers 41, the upper and lower rubber washers 43, and the sensor base 45 are retained between the lower step of the sensor frame penetrating portion 39c of the central shaft 39 and the lower nut 39e.
  • the end 45b of the sensor base 45 is fixed to the seat bracket 47 by means of a bolt which is not shown.
  • the seat bracket 47 projects from the vehicle chassis.
  • the general action of the seat weight measuring apparatus of Figs. 10(A), 10(B) will be summarized.
  • the weight of a seat and a occupant loaded on the seat rail 11 are normally transmitted via the sensor plate 37 to the central shaft 39, the rubber washers 43, the sensor base 45, and the seat bracket 47.
  • the sensor plate 37 gives rise to a deflection roughly proportional to the load which is detected by the strain gauges 37b, to measure the load acting on the sensor plate 37 in the vertical direction.
  • the weight of the occupant is obtained by summing the loads measured by the respective load sensors, front and rear on both sides, and subtracting the known weights of the seat and the seat rail from the sum.
  • the electrical output should be increased, so it is required to apply deformation distortion as large as possible to the sensor plate.
  • portions under the resistors for detecting deformation of the sensor plate are required to be deformed to obtain the maximum distortion within a range allowed by the base and the laminated layers (sensor).
  • the sensitivity is unsteady according to the distortion pattern of the sensor plate and further localized concentration occurs due to impact or the like, the strain on a portion may exceed the allowable limit and the portion may be broken.
  • the sensor plate should be made in such a manner as to disperse the deformation stress and to unify the distortion on the surface to obtain distortion corresponding to 70 % or more of the maximum distortion about the resistors on the sensor plate.
  • Figs. 11(A)-11(C) are illustrations showing a structure example of a sensor plate of the conventional seat weight measuring apparatus.
  • Fig. 11(A) is a plan view of the sensor plate
  • Fig. 11(B) shows a section taken along a line X-X' of Fig. 11(A)
  • Fig. 11(C) is a circuit diagram of the sensor.
  • the sensor plate is marked with a numeral 51.
  • a sensor 50 comprises a sensor plate (spring member) 51 as a base thereof and an insulating layer (lower insulating layer) 52 formed on the sensor plate 51 for electrical insulation.
  • a wiring layer 53 Selectively formed on the insulating layer 52 is a wiring layer 53.
  • a resistor layer 54 is selectively formed on the wiring layer 53 to compose a strain gauge.
  • an insulating layer (upper insulating layer) 55 is applied over these layers as a protective layer. In this manner, the electrical circuit including resistors is directly laminated on the spring member 51, thereby reducing the working cost and the assembly cost and further improving the heat resistance and the corrosion resistance.
  • the sensor plate 51 is a rectangular plate having two necks 52c as a whole.
  • the sensor plate 51 is provided with a central hole 51a in the center thereof and bolt holes 51 b formed in both end portions thereof.
  • the sensor 50 is formed around the central hole 51a and between the central hole 51a and the bolt holes 51 b.
  • V-shaped concaved necks are provided in opposite side edges of regions 51 c between the central hole 51a and the bolt holes 51 b. These necks ensure positions to be deformed of the sensor plate 51, thereby preventing positional variation of distortion and stabilizing the sensitivity of the sensor 50.
  • the sensor 50 is substantially symmetrical about the center of the central hole 51a. That is, the sensor 50 is composed of four resistor-type strain gauges of which two 54a, 54b to be applied with tensile distortion are arranged near the bolt holes 51 b (near the ends), and the other two 54c, 54d to be applied with compressive distortion are arranged near the central hole 51a (central side).
  • the four resistor-type strain gauges 54a, 54b, 54c, and 54d are connected to each other by wirings 53a, 53b, 53c, and 53d to form a bridge circuit shown in Fig. 11(C). Squares marked with numerals 1, 2, 3, 4 in Fig. 11(C), are terminals.
  • a sensitivity control resistor 54e Arranged between the resistor-type strain gauges 54a, 54c and the resistor-type strain gauges 54b, 54d is a sensitivity control resistor 54e. It should be noted that the load may be obtained by conversion from deflection of the sensor plate 51 detected by electrical capacitance pressure sensors or Hall elements, instead of the detection of distortion of the sensor plate 51 being detected by the resistor-type strain gauges 54a, 54b, 54c, and 54d.
  • the load is measured by causing deformation of the sensor plate 51 due to the load, detecting the distortion due to the deformation by the strain gauges 54a, 54b, 54c, and 55d shown in Fig.11(C), and detecting the output of the bridge circuit composed of these strain gauges as described above.
  • variation in value of resistance of the strain gauge depends on not only the distortion but also the temperature,. That is, when the environmental temperature of the seat weight measuring apparatus rapidly changes, the temperature of the sensor base 45 having a relatively large surface area is changed. The change in temperature is transmitted to the sensor plates 37 (51) via the bolts (sensor post) 49. A temperature difference is generated among the strain gauges 54a, 54b, 54c, and 54d on the sensor plate 51. This temperature differences produces a difference in values of resistances. Accordingly, the output of the bridge circuit composed of these strain gauges is outputted, causing error in weight measurement.
  • the present invention has been made in view of the aforementioned problems and the object of the present invention is to provide a load sensor hardly casing error in weight measurement even when the environmental temperature of the load sensor varies, and a seat weight measuring apparatus using the same.
  • a load sensor comprising a base plate which is deformed when subjected to a load and a plurality of strain gauges which are attached to said base plate to form a bridge circuit, wherein said load sensor measures a load by detecting an electrical signal from the bridge circuit, and is characterized in that said strain gauges forming the bridge circuit are attached to the front and back surfaces of said base plate at substantially the same location to compensate the variation in resistance among the strain gauges generated due to the temperature distribution of said base plate.
  • the strain gauges composing the bridge circuit are attached to the front and back surfaces of the base plate at substantially the same location, thereby compensating the variation in resistance among the strain gauges generated due to the temperature distribution of said base plate.
  • “Attached to the front and back surfaces at substantially the same location” means “attached to such positions of the front and back surfaces as to be superposed on each other as seen in the top view thereof". "Substantially the same location” means that there is some permissibility in the attached positions within such a range that the temperature compensation can be conducted to a desired accuracy.
  • the bridge circuit is structured such that the variations in resistance among the strain gauges generated due to the temperature distribution of the base plate can be compensated and the load on the base plate can be detected. In addition, it is possible to compensate the temperature.
  • An embodiment of the invention to solve the aforementioned problems is a load sensor where said strain gauges attached to the front and back surfaces of said base plate at substantially the same location are connected to adjacent sides of the bridge circuit.
  • the bridge circuit Since the strain gauges to be attached to the front surface and the back surface of the base plate at substantially the same location are connected to adjacent sides of the bridge circuit, the bridge circuit produces an output relative to variation in resistance between the strain gauges due to load variation, that is, when the resistance of one of a pair of strain gauges increases and the resistance of the other one decreases. On the other hand, the bridge circuit works to cancel variation in resistance due to temperature. Therefore, the bridge circuit is structured such that it can detect the load applied to the base plate and can conduct the temperature compensation.
  • said load sensor formed by adhering a flexible substrate made of an insulating material, on which the strain gauges, electrical components and a circuit pattern as the auxiliaries are previously mounted, to said base plate.
  • the load sensor is formed by previously mounting the strain gauges, electrical components and a circuit pattern as the auxiliaries on the flexible substrate, and adhering the flexible substrate to the base plate to be subjected to load.
  • the mounting work of the strain gauges, and the electrical components and the circuit pattern as the auxiliaries to the flexible substrate is easier than the mounting work of these components to the base plate to be subjected to load.
  • the manufacturing process for this does not require the burning. Accordingly, this embodiment provides easy manufacturing and achieves the reduction in manufacturing cost.
  • said flexible substrate composed of two insulating materials sandwiching a conductive member forming a ground pattern therebetween, and said ground pattern is in communication with a ground line mounted on the front surface of the flexible substrate.
  • a conductive member forming a ground pattern is sandwiched between two insulating materials and is in communication with a ground line mounted on the front surface of the flexible substrate via a through hole formed in one of the insulating materials or the like. Therefore, the ground pattern can be designed to have substantially the same area as the area of the flexible substrate, thereby improving the noise resistant.
  • said flexible substrate in which a conductive member forming a ground pattern is embedded, and said ground pattern are in communication with a ground line mounted on the front surface of the flexible substrate.
  • This embodiment has basically the same structure as the directly aforementioned embodiment.
  • a different point from the directly aforementioned embodiment is that the conductive material forming the ground pattern is completely enclosed by the flexible substrate made of an insulating material, thereby preventing the oxidization of the ground pattern and improving the durability.
  • a ground pattern is provided via an insulating member on at least one of the upper side and the lower side of the strain gauges, the electrical components and/or the circuit pattern, and said ground pattern is in communication with a ground line mounted on the front surface of the flexible substrate.
  • a ground pattern is provided via an insulating member on at least one of the upper side and the lower side of the strain gauges, the electrical components and/or the circuit pattern, and said ground pattern is in communication with a ground line mounted on the front surface of the flexible substrate, thereby improving the noise resistance of the load measuring circuit.
  • said ground pattern is in communication with the ground line which is mounted on the front surface of the flexible substrate via an RC parallel circuit.
  • the ground pattern is in communication with the ground line mounted on the front surface of the flexible substrate via the RC parallel circuit, surge can be effectively absorbed by adjusting values of resistance R and capacitance C.
  • a further embodiment of the invention is comprising a backing plate which is provided at a portion of said flexible substrate on which the electrical components are mounted.
  • a backing plate is provided at a portion of the flexible substrate on which the electrical components are mounted, thereby facilitating the mounting of the electrical components. It should be understood that the surface on which the backing plate is provided is opposite to the surface adhered to the base plate and the electrical components are mounted on the backing palate.
  • said strain gauges to be attached to the front and back surfaces of said base plate are mounted on a single flexible substrate and are attached to the front and back surfaces of said base plate by folding said flexible substrate and applying said flexible substrate to the front and back surfaces of said base plate.
  • the strain gauges to be attached to the front and back surfaces of the base plate are mounted on a single flexible substrate and are attached to the front and back surfaces of said base plate by folding the single flexible substrate and applying the single flexible substrate to the front and back surfaces of the base plate, the strain gauges to be attached to the front and back surfaces of the base plate can be attached to the base plate at once and the positions of the strain gauges on the front and back surfaces can be easily adjusted.
  • a seat weight measuring apparatus for measuring the weight of a vehicle seat including the weight of an occupant sitting thereon, comprising: a load sensor which is disposed inside a seat or between the seat and a vehicle body and which receives at least a part of the weight of the vehicle seat and converts the received weight into an electrical signal, and is characterized in that said load sensor is one of the load sensors mentioned above.
  • Fig. 1 is an illustration showing a load sensor of the embodiment of the present invention.
  • a numeral 51 designates a sensor plate, which is the same as the sensor plate 37 in Figs. 10(A), 10(B) and the sensor plate 51 in Figs. 11(A)-11(C).
  • the holes formed in the sensor plate 51 are marked with the same numerals as used in Fig. 11 (A). The description of the holes will be omitted.
  • the sensor plate 51 corresponds to "load sensor” in “Patent Claims” and “Mean to solve the problems”.
  • a sensor 50 is arranged on the sensor plate 51.
  • Employed as the sensor 50 in the embodiment is a sensor comprising a flexible substrate, and strain gauges and print wirings which are arranged on the flexible substrate. That is, the sensor 50 is composed of a single flexible substrate.
  • strain gauges and print wirings are formed on a thin film of polyimide.
  • Another thin film of polyimide is further formed on them so that the strain gauges and the print wirings are sandwiched by the polyimide thin films, thereby forming the flexible substrate.
  • the sensor 50 includes strain gauges 54a' through 54d' in addition to the strain gauges 54a through 54d. These strain gauges are connected to each other via the print wirings 53 shown with hatching. Each print wiring 53 has a terminal 53e through which the communication to and from the outside is established.
  • strain gauges 54a' through 54d' are provided.
  • portions of the flexible substrate on which the strain gauges 54a' through 54d' are formed are folded and adhered to the back of the sensor plate. Therefore, the strain gauges 54a' through 54d' are formed on the backs of the portions of the sensor plate 51 where the strain gauges 54a through 54d are arranged, respectively.
  • Fig. 2 is an enlarged view of a left side portion of the sensor 50 in Fig. 1.
  • the strain gauges 54a, 54c, 54a' 54c' are connected each other by the print wiring 53 as shown in Fig. 2.
  • Fig. 3 shows a bridge circuit composed of the strain gauges.
  • the basic structure of the circuit is identical to that shown in Fig. 11(C), except that the new strain gauges 54a' through 54d' are added as shown in Fig. 3.
  • the variation in distortion generated between the strain gauge 54a' and the strain gauge 54c' has an amount substantially equal to, but having an opposite sign, that distortion between the strain gauge 54a and the strain gauge 54c.
  • the variation in distortion generated between the strain gauge 54b' and the strain gauge 54d' has an amount substantially equal to, but having an opposite sign, that distortion between the strain gauge 54b and the strain gauge 54d.
  • the load sensor of this embodiment can measure the variation in load, with no or little influence due to variation in temperature.
  • the subject matter of the present invention is achieving the temperature compensation by providing additional strain gauges (corresponding to the strain gauges 54a'-54d' in this embodiment) on the back of the substrate on which conventional strain gauges (corresponding to the strain gauges 54a-54d in this embodiment) are arranged.
  • additional strain gauges corresponding to the strain gauges 54a'-54d' in this embodiment
  • conventional strain gauges corresponding to the strain gauges 54a-54d in this embodiment
  • the strain gauges and the wirings are formed on the flexible substrate by printing or the like in this embodiment, commercially available strain gauges may be attached to the substrate as the strain gauges and, and normal wirings may be used as the wirings and may be connected by wire bonding or soldering.
  • the strain gauges and wirings on the front side and the strain gauges and wirings on the back side may be formed on separate flexible substrates, respectively and the flexible substrates may be applied to the front and the back of the sensor plate, respectively. Further, only wirings are formed on a flexible substrate by printing or the like and strain gauges may be attached to the flexible substrate by wire bonding or soldering. Furthermore, a bridge circuit as shown in Fig. 3 may be formed on the flexible substrate. In addition to this, a circuit such as an amplification circuit, particularly a circuit composed of a custom IC, may be attached to the flexible substrate.
  • the strain gauges, the wirings, and the circuit are preferably sandwiched between flexible insulating members made of polyimide, thereby exhibiting the insulating effect and water-proof effect.
  • Fig. 4 is a schematic illustration showing a structure example of a load sensor circuit formed on a flexible substrate.
  • a flexible substrate 61 made of an insulating material are mounted on a flexible substrate 61 made of an insulating material.
  • an electrical component 63 such as an amplifier for processing the signal from the strain gauge 62, which are connected to each other by a print wiring 64.
  • a protective film 65 made of an insulating material is formed to wrap around the mounted objects.
  • the base plate 67 is generally made of a metallic body and has a deformable portion at least right under the strain gauge 62 where can be deformed when subjected to a load.
  • the base plate 67 may be formed to have a thinner portion to form the deformable portion.
  • the deformation is transmitted to the strain gauge 62 on the flexible substrate 61 adhered to the base plate 67 by the adhesive 66 and is converted into an electrical signal.
  • the electrical signal is processed by the electrical component 63 such as an amplifier and then is transmitted to a control device such as a CPU via a wiring which is not shown.
  • Fig. 5 shows another example of a structure comprising a flexible substrate and electrical circuit components which are mounted on the flexible substrate before adhered to the base plate 67.
  • a conductive material 68 is sandwiched between two flexible substrates 61, thereby forming a ground pattern.
  • the area of the ground pattern is made as large as possible.
  • the ground pattern is connected to a ground line composed of a print wiring 64 through a through hole 69.
  • Fig. 6 shows still another example of a structure comprising a flexible substrate and electrical circuit components which are mounted on the flexible substrate before adhered to the base plate 67.
  • This structure is substantially the same as that shown in Fig. 5.
  • a different point from that shown in Fig. 5 is that the conductive material is completely enclosed by the flexible substrate 61. This structure can prevent the oxidization of the conductive material 68 (ground pattern).
  • Fig. 7 shows yet another example of a structure comprising a flexible substrate and electrical circuit components which are mounted on the flexible substrate before adhered to the base plate 67.
  • a backing plate 70 is provided at a portion on which the electrical component 63 such as an amplifier is mounted.
  • the electrical component 63 is mounted on the backing plate 70. Since an electrical component such as an IC generally has connector pins, it may be difficult to mount the electrical component directly on the flexible substrate 61. However, the presence of the backing plate 70 can facilitate the mounting. Unlike the portion where the strain gauge 62 is attached, the portion where the backing plate 70 is mounted is not required to be deformed, preferably never deformed, no disadvantage is generated by the presence of the backing plate 70.
  • Fig. 8 shows a structure in which a ground pattern 71 is arranged inside the flexible substrate 61 so as to shield the strain gauge 62, the print wiring 64, and the electrical components 63.
  • the ground pattern 71 may be connected to a ground line composed of the print wiring 64 by a through hole.
  • a ground pattern may be arranged inside a protective layer 65.
  • the present invention can provide a load sensor hardly casing error in weight measurement even when the environmental temperature of the load sensor varies, and a seat weight measuring apparatus using the same.
EP03028475A 2002-12-26 2003-12-12 ( Sitz ) Last-Platte mit Doppelbrücke zur Temperaturkompensation Withdrawn EP1434042A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2002376643 2002-12-26
JP2002376643A JP2004205410A (ja) 2002-12-26 2002-12-26 荷重センサ及びシート重量計測装置

Publications (1)

Publication Number Publication Date
EP1434042A1 true EP1434042A1 (de) 2004-06-30

Family

ID=32463573

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03028475A Withdrawn EP1434042A1 (de) 2002-12-26 2003-12-12 ( Sitz ) Last-Platte mit Doppelbrücke zur Temperaturkompensation

Country Status (3)

Country Link
US (1) US7055365B2 (de)
EP (1) EP1434042A1 (de)
JP (1) JP2004205410A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2913219A1 (de) * 2014-02-27 2015-09-02 Delphi Technologies, Inc. Insassendetektionsvorrichtung mit Temperaturkompensation
WO2018007310A1 (de) * 2016-07-05 2018-01-11 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Bamberg Sensorbaugruppe für ein kraftfahrzeug
EP3025129B1 (de) * 2013-07-22 2021-04-07 Illinois Tool Works Inc. Flexible schaltungsschnittstelle für dehnungsmessstreifen

Families Citing this family (50)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3894879B2 (ja) * 2002-11-27 2007-03-22 本田技研工業株式会社 乗員の重量検出装置
US7342185B2 (en) * 2003-06-10 2008-03-11 The Flintec Group, Ltd. Compression column load cell with compensation for off center loading errors
US7255015B2 (en) * 2003-07-31 2007-08-14 Sensata Technologies, Inc. Occupant weight sensor for vehicular seats, method for making and system therefor
JP2005098989A (ja) * 2003-09-05 2005-04-14 Alps Electric Co Ltd 荷重センサ
JPWO2006006670A1 (ja) * 2004-07-14 2008-05-01 長野計器株式会社 荷重センサ
US7516809B2 (en) * 2004-08-31 2009-04-14 Siemens Aktiengesellschaft System and method for occupant detection and classification in motor vehicles
JP4779333B2 (ja) * 2004-10-05 2011-09-28 パナソニック株式会社 歪検出装置
US7117756B2 (en) * 2004-10-27 2006-10-10 Lear Corporation Load detecting vehicle seat assembly
JP4677769B2 (ja) * 2004-11-19 2011-04-27 アイシン精機株式会社 シート上荷重検出装置
US8436261B2 (en) * 2004-12-13 2013-05-07 Nate John Coleman Cantilever beam scale
US9360383B2 (en) 2013-04-04 2016-06-07 Nate J. Coleman and Aexius, LLC System and method to measure force or location on an L-beam
US7363184B2 (en) * 2005-02-09 2008-04-22 Trw Automotive U.S. Llc System and method for drift compensation in a seat load sensing system
US7219760B2 (en) * 2005-02-14 2007-05-22 Trw Automotive U.S Llc Seat load sensing apparatus
US20070010935A1 (en) * 2005-07-08 2007-01-11 Trw Automotive U.S. Llc System and process for adjusting a zero point of a seat load sensing system
US7455343B2 (en) * 2005-09-12 2008-11-25 Ts Tech Co., Ltd. Passenger's weight measurement device for vehicle seat and attachment structure for load sensor
ITBO20050736A1 (it) * 2005-12-02 2007-06-03 Ferrari Spa Metodo per montare un sedile provvisto di sensori di peso su di un telaio di un autoveicolo
ATE446495T1 (de) * 2006-05-30 2009-11-15 Timken Co Sensor für verschiebung, dehnung und kraft
JP4989173B2 (ja) * 2006-09-27 2012-08-01 本田技研工業株式会社 車両のばね下部材用歪検出装置
US7441464B2 (en) * 2006-11-08 2008-10-28 Honeywell International Inc. Strain gauge sensor system and method
JP4566227B2 (ja) * 2007-09-25 2010-10-20 株式会社日立製作所 半導体歪センサーおよび半導体歪センサーの取付け方法
JP2009128153A (ja) * 2007-11-22 2009-06-11 Aisin Seiki Co Ltd 車両用のシート用荷重検知センサ
KR100941252B1 (ko) * 2007-12-17 2010-02-10 현대모비스 주식회사 2개의 하중감지기를 이용한 승객식별장치
US20090179764A1 (en) * 2008-01-15 2009-07-16 Chul-Sub Lee Device For Detecting Passenger's Weight In Vehicle
JP5446592B2 (ja) * 2009-08-24 2014-03-19 アイシン精機株式会社 車両衝撃判定装置、車両衝撃判定方法および車両衝撃報知装置
US8482868B2 (en) * 2010-07-15 2013-07-09 Newport Corporation Optical adjustable mounts with absolute position feedback
LU92011B1 (en) 2012-05-30 2013-12-02 Iee Sarl Vehicle seat suspension mat
LU92013B1 (en) * 2012-05-30 2013-12-02 Iee Sarl Vehicle seat suspension mat
JP2014221605A (ja) * 2013-05-14 2014-11-27 アイシン精機株式会社 車両用シート装置の体重検知センサ
JP6127702B2 (ja) * 2013-05-14 2017-05-17 アイシン精機株式会社 体重検知センサ及び車両用シート装置
JP6092044B2 (ja) * 2013-08-19 2017-03-08 ミネベアミツミ株式会社 荷重センサユニット
US9425711B2 (en) 2014-04-15 2016-08-23 Newport Corporation Integral preload mechanism for piezoelectric actuator
US9580042B2 (en) * 2014-07-09 2017-02-28 National Association For Stock Car Auto Racing, Inc. Strain gage load cell anchor
LU92553B1 (en) * 2014-09-22 2016-03-23 Iee Sarl Weight-responsive vehicle seat occupancy classification system
WO2016123265A1 (en) 2015-01-29 2016-08-04 Newport Corporation Integrated picomotor mount
JP6373778B2 (ja) 2015-03-11 2018-08-15 アルプス電気株式会社 荷重センサおよび荷重検出装置
US9901515B2 (en) * 2015-05-07 2018-02-27 Perfomance Designed Products LLC Smart cap for medication container
JP6198804B2 (ja) * 2015-12-01 2017-09-20 日本写真印刷株式会社 多点計測用のひずみセンサとその製造方法
DE102015016205A1 (de) 2015-12-14 2017-06-14 GM Global Technology Operations LLC (n. d. Ges. d. Staates Delaware) Kraftfahrzeug-Sitzanordnung-Belegungserfassung
JP2017146134A (ja) * 2016-02-16 2017-08-24 アルプス電気株式会社 抵抗値調整回路および荷重検出装置ならびに抵抗値調整方法
JPWO2018003527A1 (ja) * 2016-07-01 2019-04-18 ソニー株式会社 センサ、センサモジュール、ウェアラブル端末および電子機器
CN105975137B (zh) * 2016-07-07 2020-11-03 上海天马微电子有限公司 一种触控显示面板及触控显示装置
JP6642394B2 (ja) * 2016-11-30 2020-02-05 株式会社デンソー 歪み検出装置
EP3410088B1 (de) * 2017-05-29 2020-02-12 Aisin Seiki Kabushiki Kaisha Lastsensor
JP2019078726A (ja) 2017-10-27 2019-05-23 ミネベアミツミ株式会社 ひずみゲージ、センサモジュール
JP2019128183A (ja) 2018-01-22 2019-08-01 ミネベアミツミ株式会社 センサモジュール
JP2019174387A (ja) 2018-03-29 2019-10-10 ミネベアミツミ株式会社 ひずみゲージ
DE102019105342A1 (de) * 2019-03-04 2020-09-10 Khs Gmbh Behälterbehandlungsanlage, Behälterträger und Verfahren zum Befüllen von Behältern
WO2021134008A1 (en) 2019-12-24 2021-07-01 Joyson Safety Systems Acquisition Llc Apparatus and method of producing a sensing substrate
JP2022133175A (ja) * 2021-03-01 2022-09-13 株式会社タニタ ロードセル、秤、及び歪センサ
JP2023143451A (ja) * 2022-03-25 2023-10-06 Koa株式会社 荷重センサ素子

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2118305A1 (de) * 1970-04-22 1971-11-11 Kyowa Electronic Instruments Lastmeß vorrichtung
US4432247A (en) * 1980-11-29 1984-02-21 Tokyo Electric Co. Load cell having thin film strain gauges
US4903000A (en) * 1987-12-03 1990-02-20 Ngk Insulators, Ltd. Pressure sensor having means for electromagnetically shielding resistors
CH673893A5 (en) * 1988-02-12 1990-04-12 Mettler Toledo Ag Temp. compensated load sensor with strain-gauge transducer - incorporates electromechanically active resistances in bridge circuit with thermal couplings to passive resistances in neighbouring branches
EP0962362A2 (de) * 1998-06-05 1999-12-08 Takata Corporation Sitzgewichtsmessgerät
US6098464A (en) * 1995-12-04 2000-08-08 Societe Nationale D'etude Et De Construction De Moteurs D'aviation Wheatstone bridge with temperature gradient compensation

Family Cites Families (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4267724A (en) * 1979-01-08 1981-05-19 Bofors America, Inc. Strain-gage transducer bridge gages with integral calibration resistors
US4217785A (en) * 1979-01-08 1980-08-19 Bofors America, Inc. Erasable-foil-resistance compensation of strain gage transducers
US4331035A (en) * 1979-11-13 1982-05-25 Gould Inc. Geometric balance adjustment of thin film strain gage sensors
US4261429A (en) * 1979-12-19 1981-04-14 Hottinger Baldwin Measurements, Inc. Unitized weighing apparatus and method for making such an apparatus
US4556115A (en) * 1983-06-17 1985-12-03 Hottinger Baldwin Measurement, Inc. Method and means for equalizing the measuring sensitivity of a plurality of strain gage transducers
US4848493A (en) * 1988-10-20 1989-07-18 Revere Corporation Of America Load sensing structure for weighing apparatus
US4898255A (en) * 1989-01-17 1990-02-06 Toledo Scale Corporation Planar load cell
US4979580A (en) * 1989-10-10 1990-12-25 Flintab Force measuring device with sensitivity equalization
US4993506A (en) * 1989-12-11 1991-02-19 Shlomo Angel Mass-produced flat one-piece load cell and scales incorporating it
US5222398A (en) * 1990-11-01 1993-06-29 Eastman Kodak Company Thin film precision load cell
US5512713A (en) * 1991-12-27 1996-04-30 Ishida Co., Ltd. Load cell having a hollow and a strain gauge formed on a substrate attached inside the hollow
US5289722A (en) * 1992-04-27 1994-03-01 Kansas State University Research Foundation Preassembled, easily mountable strain gage
US5375474A (en) * 1992-08-12 1994-12-27 The United States Of America As Represented By The United States National Aeronautics And Space Administration Compensated high temperature strain gage
DE4236985C1 (de) * 1992-11-04 1994-02-24 Hottinger Messtechnik Baldwin Dehnungsmeßstreifen
US5573269A (en) 1993-12-02 1996-11-12 Trw Vehicle Safety Systems Inc. Apparatus and method for sensing and restraining an occupant of a vehicle seat
US5510581A (en) * 1994-05-18 1996-04-23 Angel; Shlomo Mass-produced flat multiple-beam load cell and scales incorporating it
US5929390A (en) * 1994-09-14 1999-07-27 Ishida Co., Ltd. Load cell weighing apparatus using the same
JP4079479B2 (ja) 1997-06-13 2008-04-23 タカタ株式会社 車両のシート装置及びエアバッグ装置
US6039344A (en) 1998-01-09 2000-03-21 Trw Inc. Vehicle occupant weight sensor apparatus
JP3655745B2 (ja) 1998-04-16 2005-06-02 タカタ株式会社 シート重量計測装置
JP3468728B2 (ja) 1998-10-06 2003-11-17 タカタ株式会社 シート重量計測装置
JP4129336B2 (ja) 1999-03-09 2008-08-06 タカタ株式会社 シート重量計測装置
US6244116B1 (en) * 1999-08-16 2001-06-12 Cts Corporation Automobile seat weight sensor
US6161891A (en) * 1999-10-21 2000-12-19 Cts Corporation Vehicle seat weight sensor
US6231076B1 (en) * 1999-11-16 2001-05-15 Cts Corporation Automobile seat having seat supporting brackets with a stepped weight sensor
US6555767B1 (en) * 2000-08-22 2003-04-29 Flintec, Inc. Composite load cell
JP3694450B2 (ja) 2000-09-18 2005-09-14 アルプス電気株式会社 荷重センサ
US6467361B2 (en) * 2001-03-20 2002-10-22 Cts Corporation Strain gage sensor having an unstrained area
JP2003004562A (ja) * 2001-06-18 2003-01-08 Alps Electric Co Ltd 入力装置ならびに検出装置
US6910392B2 (en) * 2003-02-20 2005-06-28 The Flintec Group, Ltd. Bending beam load cell with torque sensitivity compensation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2118305A1 (de) * 1970-04-22 1971-11-11 Kyowa Electronic Instruments Lastmeß vorrichtung
US4432247A (en) * 1980-11-29 1984-02-21 Tokyo Electric Co. Load cell having thin film strain gauges
US4903000A (en) * 1987-12-03 1990-02-20 Ngk Insulators, Ltd. Pressure sensor having means for electromagnetically shielding resistors
CH673893A5 (en) * 1988-02-12 1990-04-12 Mettler Toledo Ag Temp. compensated load sensor with strain-gauge transducer - incorporates electromechanically active resistances in bridge circuit with thermal couplings to passive resistances in neighbouring branches
US6098464A (en) * 1995-12-04 2000-08-08 Societe Nationale D'etude Et De Construction De Moteurs D'aviation Wheatstone bridge with temperature gradient compensation
EP0962362A2 (de) * 1998-06-05 1999-12-08 Takata Corporation Sitzgewichtsmessgerät

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3025129B1 (de) * 2013-07-22 2021-04-07 Illinois Tool Works Inc. Flexible schaltungsschnittstelle für dehnungsmessstreifen
EP2913219A1 (de) * 2014-02-27 2015-09-02 Delphi Technologies, Inc. Insassendetektionsvorrichtung mit Temperaturkompensation
US9227526B2 (en) 2014-02-27 2016-01-05 Delphi Technologies, Inc. Occupant detection device with temperature compensation
WO2018007310A1 (de) * 2016-07-05 2018-01-11 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Bamberg Sensorbaugruppe für ein kraftfahrzeug

Also Published As

Publication number Publication date
JP2004205410A (ja) 2004-07-22
US7055365B2 (en) 2006-06-06
US20040124018A1 (en) 2004-07-01

Similar Documents

Publication Publication Date Title
US7055365B2 (en) Load sensor and seat weight measuring apparatus with a plurality of strain gauges
US6345543B1 (en) Seat weight measuring apparatus
US6571647B1 (en) Seat weight measuring apparatus
US6323444B1 (en) Seat weight measuring apparatus
JP3468728B2 (ja) シート重量計測装置
US6323443B1 (en) Seat weight measuring apparatus
US7490523B2 (en) Occupant load detecting device of seat for vehicle
US6997060B2 (en) Load-detecting device
JP4221041B2 (ja) 荷重検出装置を備えた車両用シート装置
US6969809B2 (en) Vehicle seat weight sensor
US20030033885A1 (en) System and method for microstrain measurement
US20070240524A1 (en) Printed Strain Gauge for Vehicle Seats
US6586948B1 (en) Vehicle seat weight measuring device
US7509871B2 (en) Occupant load sensor for vehicle
CA2360261C (en) Fixing structure for sensing element
US20030066362A1 (en) Seat belt tension sensor
JP2834282B2 (ja) ロードセル
JP5003430B2 (ja) 車両用シート荷重検出装置
JP3444810B2 (ja) シート重量計測装置
US6499360B1 (en) Torsional sensing load cell with overload protection
JP4129336B2 (ja) シート重量計測装置
JP6127702B2 (ja) 体重検知センサ及び車両用シート装置
JP3663406B2 (ja) シート重量計測装置
US20050242554A1 (en) Seat load measuring device and occupant protection system using the same
WO2006099746A1 (en) Automotive weight sensor for occupant classification system

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK

17P Request for examination filed

Effective date: 20041228

AKX Designation fees paid

Designated state(s): DE FR GB SE

17Q First examination report despatched

Effective date: 20050311

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20060725